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Sunday, May 13, 2012

Prehistoric Elephants

Recently I drew a Platybelodon and uploaded it to Deviantart, proclaiming my love for extinct elephants (and other afrotheres, and other "pachyderms"). So let's talk about elephants, shall we?

Elephants, formally known as proboscideans, first appeared in the fossil record some 58.7 million years ago, in the late Paleocene. The first of the proboscideans known is named Eritherium and it was the size of a large rabbit (~5kg). Yeah, you heard the books call  Moeritherium small. The  slightly bigger (fox-sized) Phosphatherium followed about two million years later. Both of these tiny elephant ancestors hailed from Morocco, home of Casablanca. The amphibious anthracobunids followed next, and were probably ancestral to moeritherids and desmostylians, and possibly the sirenians. This family existed from the Early-Middle Eocene.

More proboscideans began to rise in the Eocene. One of these was the somewhat famous Moeritherium, the rotund little hippopotamus-niche filler. It is often stated as one of the earliest elephant genera, but has seen above, Eritherium came earlier before they were cool. Fellow proboscideans Phiomia and Palaeomastodon, the latter already similar to modern-day elephants coexisted with Moeritherium. Phiomia probably used its upper tusks to strip bark off trees, while Palaeomastodon is thought to have scooped water plants into its mouth. Also from the Late Eocene was Barytherium, which sported eight (though short and stubby) tusks. Showoff.

During the Oligocene, families were either diversifying or dying off. Brontotheres were part of the latter decision, as were embrithopods and multituberculates. As forests gave way to plains, horses, camels, rhinos, entelodonts, and oreodonts diversified. Elephants also diversified. By the late Oligocene, a bizarre family had sprouted up; the deinotheres. Chilgatherium was the earliest known deinothere,  the size of a small hippo. It is unknown if it had the bizarre downwards pointing tusks that makes the family famous and earns them the nickname "hoe-tuskers". Time went on, and in the middle Miocene, when Prodeinotherium died out, Deinotherium arose. This deinothere proved to be the most successful as it only went the way of the dodo in the Early Pleistocene. D. giganteum was one of the largest terrestrial mammals ever known, exceeded only by a few mammoths and the giant rhino Paratherium.

Equally as bizarre were the gomphotheres, a family from the Miocene to the Pleistocene eras. A very diverse family, they flourished and enjoyed ecological success. One of the most famous is the "shovel-tusker" Platybelodon, seen above. With tusks on its long lower jaws, and the typical tusks found on modern elephants, it is thought to have scraped bark off of trees and consume branches. There were other "shovel-tuskers" as well, such as Amebelodon and Archaeobelodon. Another somewhat well-known gomphothere was Anancus. Why? Just look to the upper right and you'll see why. It's those really long tusks that make it stand out. Yep, each tusks measures 13ft long, slightly longer than the elephant is tall. How's that for a trophy?

Another famous gomphothere is the one that gives the family its namesake. Gomphotherium, 10ft tall, sported four tusks and probably inhabited dry wooded regions by lakes, or perhaps swamps to boot. It was also one of the most successful gomphotheres as it spread into Afro-Eurasia, North America, and possibly South America (in Chile) as well. The last gomphothere we'll talk about is Cuvieronius, a 9ft tall elephant with spiral tusks. It is the most recent of the gomphotheres, dying out just 6,000 years ago. Named after George Cuvier, it has been found in the US, Mexico, and South America.

Now we touch on the most famous prehistoric elephants of all: mammoths and mastodons. While the former term is often used to describe something large in size, it technically defines anything that belongs to the genus Mammuthus. Of that genus, eleven species have been described: M. meridionalis, M. trogontherii, M. imperator, M. exilis, M. subplanifrons, M. africanavus, M. columbi, M. lamarmorae, M. hayi, M. creticus, and most famous of all, M. primigenius, the woolly mammoth. In common terms, that's, respectively: the southern, steppe, imperial, pygmy, African, North African, Columbian, Sardinian dwarf, (no common name), and the Cretan dwarf mammoths. Despite their large numbers, the mammoths existed in a short window of time, only 5 million years. Despite these numbers, there were able to inhabit Afro-Eurasia and North America, ranging in size from 3-17ft tall. The woolly mammoth isn't actually as "mammoth" as some may think, standing "only" 9ft tall, and when compared to the steppe and southern mammoths, it looks quite small.

Mastodons, known by the genus Mammut, are often confused with mammoths by laymen, by there are several differences. Mastodons were usually smaller and lacked the classic dome head, and had different dentition than mammoths. Seven species have been described in the genus: M. furlongi, M. matthewi, M. raki, M. spenceri, M. pentilicus, M. cosoensis, and the classic American mastodon M. americanum. It would have lived in spruce forests, as well as warmer lowlands, and it went extinct only 10,000 years ago.

All in all, elephants proved to be one of the most successful families in history, carrying on a legacy that has lasted for 55 million years. From the tiny Eritherium they blossomed into the five ton African elephant and became some of the largest terrestrial mammals.
In respective order:

© Vladimir Nikolov.
© BBC and Impossible Pictures.
© Dmitry Bogdanov.
© Boris Dimitrov.
© Remy Bakker.
© Charles R. Knight.
© Mauricio Anton.
© Sergio De la Rosa Martinez.

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